endtmesh(3G)

NAME
     bgntmesh, endtmesh - delimit the vertices of a triangle mesh

C SPECIFICATION
     void bgntmesh()

     void endtmesh()

PARAMETERS
     none

DESCRIPTION
     Vertices specified between bgntmesh and endtmesh are used to define a
     mesh of triangles.  The graphics pipe maintains two vertex registers.
     The first and second vertices are loaded into the registers, but no
     triangle is drawn until the system executes the third vertex routine.
     Upon executing the third vertex routine, the system draws a triangle
     through the vertices, then replaces the older of the register vertices
     with the third vertex.

     For each new vertex routine, the system draws a triangle through the new
     vertex and the stored vertices, then (by default) replaces the older
     stored vertex with the new vertex.  If you want the system to replace the
     more recent of the stored vertices, call swaptmesh prior to calling v.

     Between bgntmesh and endtmesh you can issue the following Graphics
     Library routines:  c, color, cpack, lmbind, lmcolor, lmdef, n, RGBcolor,
     swaptmesh, t, and v.  Use lmdef and lmbind only to respecify materials
     and their properties.

     If you want to use backface, you should specify the vertices of the first
     triangle in counter-clockwise order.  All triangles in the mesh have the
     same rotation as the first triangle in a mesh so that backfacing works
     correctly.

     There is no limit to the number of vertices that can be specified between
     bgntmesh and endtmesh.

     By default triangle vertices are forced to the nearest pixel center prior
     to scan conversion.  Triangle accuracy is improved when this coercion is
     defeated with the subpixel command.  Subpixel vertex positioning is
     especially important when triangles are scan converted with antialiasing
     enabled (see polysmooth).

     After endtmesh, the current graphics position is undefined.

EXAMPLE
     For example, the code sequence:
          bgntmesh();
          v3f(v0);
          v3f(v1);
          v3f(v2);
          v3f(v3);
          endtmesh();


     draws two triangles, (v0,v1,v2) and (v3,v2,v1), while the code sequence:

          bgntmesh();
          v3f(v0);
          v3f(v1);
          swaptmesh();
          v3f(v2);
          v3f(v3);
          endtmesh();


     draws two triangles, (v0,v1,v2) and (v0,v2,v3).  There is no limit to the
     number of times that swaptmesh can be called.

NOTE
     On Impact and Infinite Reality lmcolor cannot be called between bgntmesh
     and endtmesh

SEE ALSO
     backface, c, concave, frontface, polymode, polysmooth, scrsubdivide,
     defpattern, shademodel, subpixel, swaptmesh, v